1. Field of the Invention
The present invention relates to an optical measuring apparatus for measuring an eye, and more particularly, to an optical measuring apparatus for automatically measuring various optical characteristic such as the refractive power of the eye, the curvature of the cornea or the like.
2. Description of the Related Art
An automatic refractometer (apparatus for automatically measuring the refractive power of an eye) and an automatic keratometer (apparatus for automatically measuring the curvature of a cornea) and the like are known as optical apparatuses for examining an eye. According to these apparatuses, a measuring optical system is constructed by having the eye disposed at a predetermined position of the optical axis thereof. The disposition of the eye requires the following two conditions: The optical axis of the apparatus is aligned by the optical axis of the eye, i.e., optical axes-aligned condition is obtained and the focal point of the optical system of a monitoring camera provided in the apparatus coincides with the eye disposed on the measuring optical system of the apparatus, i.e., an in-focus condition is obtained. The automatic refractometer observes, through the optical system, an optical target (measuring light) whose image is formed on the eyeground of the eye, namely, on the retina, thus automatically measuring the refractive power of the eye. In order to measure the refractive power of the eye, before the measuring lights are projected, the positions of the measuring optical system of the apparatus and the eye are adjusted to a measurable condition, namely, a condition in which optical axes of the optical system and the eye align with each other and the measuring lights projected by the light projecting optical system are focused on the eye. According to known automatic refractometers, before the examination of the eye is started, the apparatus is moved lengthwise and widthwise so that the position of an axes-aligning mark (reticle pattern) and the position of the image of a light reflected by the cornea displayed on the monitor screen align with each other. Thus, an optical axes alignment is accomplished. In addition, the distance between the apparatus and the eye is adjusted. Thus, the focal point of the optical system of the monitoring camera of the apparatus coincides with the position of the eye disposed on the measuring optical system thereof. As described above, in order to measure the refractive power of the eye, it is necessary for an operator to confirm that optical axes-aligned and in-focus condition have been obtained on the monitor screen and then, to turn on a measuring start switch.
However, according to the above-described method for examining the eye, it is difficult for a patient to keep the same posture when optical axes-aligned and in-focus conditions have been obtained. In practice, it is very difficult for the operator to turn on the switch immediately after the optical axes-aligned and in-focus conditions are obtained. That is, the operator must be skilled in the timing of turning on the measuring start switch.